The practice of placing a small amount of tobacco in the gingivobuccal groove and leaving it there for extended periods of time is known as "snuff dipping". Most Americans regard the snuff dipper as a quaint character. This quaint character however, is the source of a thriving multi-million dollar business in the Rocky Mountain region, the Northwest, and the South. Wynder and co-workers (1) have called attention to the high incidence of cancer of the lip and buccal mucosa in the southern part of the United States. They have also pointed out that buccal mucosal carcinomas are often located in precisely the ares where chewing tobacco or snuff is held in the mouth. Greer and Wilson (2) have reported similar finding in the Rocky Mountain region. Smokeless chewing tobacco appears to be finding its way into middle, high school, and college campuses in Colorado as a socially acceptable and vastly populat habit that reflects a macho image (3). The present research proposal is designed to increase public and scientific knowledge regarding teenage utilization of smokeless tobacco and to document the clinical and histologic characteristics of smokeless tobacco related oral mucosal atypia and verrucous carcinoma in a teenage population. A second goal of the project is to determine if there are histochemical differences between verrucous carcinoma and the more commonly encountered squamous cell carcinoma of the oral cavity. The possibility that a tobacco virus or an indigenous oral cavity viral mutagen may induce the disease will be investigated on a morphologic basis using ultrastructural evaluation of tissue samples.